Of the 5.7 million stroke survivors in the United States, the vast majority exhibit significant arm weakness (called "hemiparesis"). This devastating impairment undermines performance of valued activities and quality of life. Yet, conventional affected arm strategies have negative evidence, or no evidence, supporting their use. Newer rehabilitative approaches emphasize repetitive, task-specific practice (RTP) incorporating the affected arm. However, many of these promising regimens require participation in intensive therapies, and most are only efficacious on the least impaired patients. Thus, there remains a need for an efficacious, practical RTP technique to address moderate to severe affected arm hemiparesis. To address above shortfalls, an innovative brace integrating electromyography (EMG) and robotics has been developed. Data collected by a study team member suggest that use of the brace (called "the Myomo") in conjunction with RTP reduces affected arm impairment in moderately impaired, chronic stroke patients. As a next step, this efficacy study will randomize 30 chronic stroke patients exhibiting moderate affected arm deficits to receive: (a) Myomo combined with RTP (Myomo + RTP);(b) RTP only (RTP);or (c) Myomo therapy only (Myomo). This study design will address the objective of the application, which is to collect randomized, controlled pilot data estimating Myomo clinical effectiveness. Based on the study team's clinical experiences and pilot data with the brace, the central hypothesis is that subjects administered Myomo therapy in combination with RTP will exhibit significant impairment reductions. Outcomes include affected arm impairment (primary endpoint), activity restriction in the lab and community, quality of life and kinematics. The PIs will test their central hypothesis and accomplish their objective by pursuing the following specific aims: (1) Compare efficacy of Myomo + RTP with RTP only and Myomo only on affected arm impairment;(2) Determine the impact of Myomo + RTP on affected arm outcomes;(3) Estimate the effect of Myomo + RTP on movement kinematics. PUBLIC HEALTH RELEVANCE: Stroke is the leading cause of disability in the United States, producing motor impairments that compromise performance of valued activities. Hemiparesis is particularly disabling, is the primary impairment underlying stroke-related disability, and the most frequent impairment treated by therapists in the United States. This study will test efficacy of a promising technique in reducing disability and increasing function, thereby improving outcomes and health, and reducing care costs, for community dwelling patients with stroke-induced hemiparesis.